Abstract
Visual processing of fearful scenes provides important cues for human to avoid potential dangers. Using functional Magnetic Resonance Imaging (fMRI), we demonstrated that brain activation in fusiform gyrus (FG) and lateral occipital complex (LOC) correlates with the levels of fearfulness of the scenes (Guo et al., 2012, SFN). However, if this activity represents affective perception of the fearful scenes, it should be invariant to manipulations of low-level stimulus features as long as the manipulation would not alter perceived fearfulness of the scenes. In a factorial design we used fMRI to measure brain activation corresponding to participants observing natural scene pictures with 5 levels of fearfulness × 2 image sizes (small: 200×200 pixels, large: 600×600 pixels). Participants viewed each fearful scene for 2s in a random order and were asked to judge the scene presented was scary or not. By using intact fearful scenes versus scrambled scenes, regions of interests (ROIs) were functionally localized in FG and LOC in each participant with separate scan runs and different stimuli set that was not used in the main experimental runs. Consistent with previous findings, a GLM analysis indicated that there is a linear relationship between brain activation in LOC and FG with the levels of fearfulness. More interestingly, large fearful scenes led to greater MR activity in both LOC and FG than small fearful scenes. Apparently, low-level visual features, such as image size, would actually influence the representations of fearful scenes in LOC and FG. These results may question the thought of functional roles of these brain regions.
Meeting abstract presented at VSS 2013